Brake mechanism



July 20, 1965 Filed March 8, 1963 M. L. CRIPE 3,195,309

BRAKE MECHANISM 2 Sheets-Sheet 2 IN VENTOR.

MAXWELL L CRIPE.

,4 7'TORNE Y.

United States Patent 3,195,369 BRAKE MECHANESM Maxwell L. Cripe, SouthBend, Ind, assignor to The Bendix Corporation, South Bend, Ind, acorporation of Delaware Filed Mar. 8, 1963, Ser. No. 263,933 4 Claims.(Cl. 60-545) This invention relates to a device for a power brake systemto reduce the effect of worn brake shoes during manual brakeapplication. More particularly, my device is concerned with reducingdisplacement necessary for brake application manually.

As brake shoes become worn from repeated use over a period of time, thedisplacement necessary to bring the shoes into contact with the brakedrum increases. With a power brake system the large amount of travelavailable to the power unit compensates for such Wear problems. However,in the event of power failure and worn shoes 21 driver is suddenlyconfronted with a large travel of the brake pedal before experiencingany vehicle deceleration. Such a problem can usually be remedied bypumping the brake pedal several times to increase the fluid within thesystem beyond the manually operated pressure intensifying means. This,as is readily obvious, increases the response time, and is somethingwhich must be remembered. It is the principal object of this inventionto provide a device which will automatically pump the system up in theevent of power failure with worn shoes.

Another object of my invention is to provide a device normallyrestrained by an operating power brake system which is released byfailure of the power brake system to displace a piston causingpressurization of a fluid on one side of the piston and a cavitation onthe other to draw a fluid from a reservoir to take up the displacementautomatically.

A further object of my invention is to provide a displacement take-updevice, as aforementioned, which is held inoperative until a brakeapplication is demanded by an operator.

Still further objects and advantages can be seen in the followingdescription of the drawings in which:

FIGURE 1 is a schematic system presentation showing a device inaccordance with my invention in sectional form;

FIGURE 2 is another schematic system presentation with a sectionaldevice in accordance with my invention as applied to a different type ofpower system than that of FIGURE 1; and

FIGURE 3 is an enlarged sectioned view of a latching mechanism such asis found in FIGURE 1.

In more detail, in FIGURE 1 I show a brake pedal operatively connectedto a master cylinder 12 to pressurize a fluid and force the piston 14 ofa power brake control valve 16 to close communication of chambers 18 and28. By further movement of pedal 10, the piston 14, after sealing withpoppet 22, will force poppet 24 to unseat and communicate an atmosphericport 26 wit chamber 18. 7

When port 26 and chamber 18 are communicated, as above, atmosphericpressure is communicated by conduit 28 to chamber 30 within a housing32. As seen, a movable wall or diaphragm 34 separates the housing intotwo variable volume chambers 36 and 36. Chamber 36 is communicated atall times to chamber 26 of valve 16 by way of a passage 38, whichchamber 26 is open to an intake manifold of a vehicle engine (not shown)via a check valve 42 and conduits 44 and 46.

Normally, the valve 16 is in the attitude shown by FIGURE 1 wherechambers 18, 2t), 30 and 36 are vacuum suspended. When, however, thepiston 14 is moved, as above, atmosphere directed to chambers 18 and 36causes "ice diaphragm 34 to abut on a tubular shaft 56 which in turnabuts against a tubular shaft 58 to compress a spring 48. A piston 58integral with a shaft 62 is mounted within a chamber 52 in a housing 51,which housing also receives shaft 58 in a bearing support 66 behind saidpiston. The shaft or force transmitting rod 62 has a radial flange 64and is affixed to piston 58 by a pin 66 and slidably mounted withinshaft 56. Thus, as the diaphragm 34 moves to' compress spring 48 shafts56 and 58 are forced to move shaft 62 by abutment with flange 64 toforce pin 66 to translate piston 50 in chamber 52 and transmitpressurized fluid via conduit 54 to wheel cylinders (not shown) of avehicle braking system. As one skilled in the art may readily expect, Iprovide a bleed orifice (not shown) in piston 58 to replenish chamber 52as required. This orifice is normally open when the piston is to therear of chamber 52, as shown.

In the event of a power failure, and in cases of power failure and/ orwith worn shoes, the fluid in chamber 52 may not be sufficientlypressurized until pedal 10 has almost reached runout. This would requirepumping to insure adequate braking. However, in cases where the driverdoes not realize the situation until too late to pump the pressure up,he quite often cannot stop in time. Therefore, I have attached a housing68 to housing 32, and as in the latter housing I have provided a movablewall 70 within housing 68 dividing it into two variable volume chambers72 and 74. The movable wall or diaphragm 70 is provided with a stubshaft 76 having a recessed portion 78 with a conically shaped end toprovide ramp surfaces 88. The stub shaft is slidably mounted in a boreof a member 82 bolted to the housing 68. A spring 84 is placed inchamber 72 to bias the movable wall 70 to the right, as viewed in FIGURE1, and the shaft 62 has a shoulder 86 for abutment with said movablewall. The shaft 62 is, as seen, of lesser diameter to the left of theshoulder to be slidably received by the stub shaft 76 connected to thediaphragm.

The member 82 is provided with a bore 88 slidably mounting a pawlmechanism 90 having an upwardly extending finger 92 with an angled face94. The pawl mechanism is provided with radial flanges 96 and 98inclosing a chamber 100 (see FIGURE 3). Between the flanges the bore 88is'drilled,as at 102, to form an inlet to chamber 190, and a conduit 104is connected to the inlet to communicate pressure from the mastercylinder 12 to chamber 180. A spring 106 is compressed between flange 98and an end plug 108 closing bore 88, and a set screw 118 is threadedthrough member 82 to engage the finger 92. The spring and set screwprovide adjustable resistance for operation of the pawl mechanism.

The reservoir of the master cylinder 12 is connected by a conduit 112 tothe area behind piston 50 in chamber 52 via a check valve 114 so thatreservoir fluid may be drawn into this area as hereinafter explained. Inaddition, chamber 72 is connected by conduit 46 to the engine intakemanifold via the check valve 42.

In operation, nothing will happen in housing 68 as long as vacuum isavailable in intake manifold 40 and the brakes have not been applied bypedal 10. As soon as pedal 10 is stroked finger 92 is forced down to beremoved from recess 78, but as vacuum is available in chamber 72 andatmosphere is in chamber 74, due to an atmosphere opening 116, diaphragm'70 remains, as seen in FIG- URE 1. If, however, vacuum is lost spring84 will force the wall 76 and, in turn, the shaft 62 by abutment onshoulder 86 to move piston 50 to the right to create a void behind thepiston which draws fluid past valve 114 from the master cylinderreservoir. As the piston 50 moves to the right fluid is transmitted tothe wheel cylinders as before to expand brake means (not shown) intoengagement with a brake surface (not shown). Thus,

further force on pedal will increase braking pressure at a lesser amountof pedal travel than heretofore available without my pumping means.

As for FIGURE 2, I show another embodiment for my invention,.i.e., in afull hydraulic power brake system. In more detail, I show a hydraulicfluid reservoir having a return port and two' supply ports 122 and 124.From port 122 I draw the fluid, as by a pump 126, driven by a vehicle.engine to supply a power brake valve means 123 via a check valve whichcheck valve permits manual brake application by a pedal 132 in that thebrake system is closed from the pump or .power system. The reservoirsupply port 124 is connected to a check valve 134.

From the power brake valve means pressurized fluid is communicated to apumping mechanism 135 in accord ance with my invention.Moreparticularly, pressurized fluid from valve 128 is fed via conduits138 and 14% to a pair of chambers 142 and 144. chamber is defined by ahousing 146 and a spring piston 148, which piston 148 also forms avariable volume chamher 151) within the housing.

The housing 146 is enlarged to form a large diameter cylinder 152 Withinwhich a wallor piston .154 is slidably mounted. To the right of the wallfluid from the pump 126 is introduced, as through port 156; whereas, thearea to the left of the wall is open to atmosphere as at 158. The wallis provided with a central portion 160 which projects to the left, asseen in FIGURE 2, and on the right end is adapted to slidably receive aforce transmitting rod 162. The portion 16% is formed on its left end orthe end opposite that receiving rod 162 with a recess 164 and a terminalportion in having a cone shaped surface 16d.

The force transmitting rod is sealingly supported by cylinder 152 andhousing 146 to project into chamber 144 and abuttingly contact piston14%. The rod carries a seal member 168 which is aligned withan opening176 through piston 143 leading a chamber 159, and asllong as rod 152 andpiston 148'are contacting each other chambers 144 and are sealed fromeach other, but when piston 148 moves away from seal 1&3 the chambers14d and 1511 are in communication.

I also provide a latch mechanism 172 comprising a 1 finger 1741having anangled face 176 operated by a.

spring biased piston 178 within chamber 142, which piston due to aspring 181i, in absence of pressure in chamber 142, normally urgesfinger 174 to project into recess 16 1 to hold the piston 154 to therear of cylinder 152.

By way of describing the operation of my device depicted by FIGURE 2, anoperator would depress pedal 132 to normally schedule power braking.However, if for some reason, such as pump failure, the depressing ofpedal 132 would cause a' pressurized fluid to force check The last.mentioned,

valve 134 to close oil the power supply system from the a brake valve128 and, thus, send-the pressurized fluid to chambers 142 and 144. Inchamber 142 piston 178 will then move to the position shown to retractthe finger 174 as shown. This releases piston 154 and as no powerpressurized fluid is entering inlet 156, atspring 182 causes piston 154to move to the right'projecting rod 162 further into chamber 154 to movepiston 148 from a stop 184 creating a void in chamber 144. This void isfilled by fiuid from reservoir 118 flowing, as "by gravity flow throughvalve 134. Therefore, Worn shoe displacement is automatically taken upand further depression of pedal of a brake pedal by a vehicle operator,which means comprises:

a power brake control means operatively connected to the brake pedal;

a hydraulic fiuid'reservoir in communication with said power brakecontrol means;

a fluid pressure intensifying means including a housing having a boretherein within which a piston is operatively arranged to divide saidbore into a first variable volume chamber and a second variable volumechamber, which housing is provided with a discharge port for said firstvariable volume chamber and a valve port and an inlet port for saidsecond variable volume chamber;

conduit means connecting said discharge port to said brake system, saidvalve port to said hydraulic fluid reservoir and said inlet port, tosaid-power brake control means; I

a force transmittingrod operatively connected to said piston;

a fluid pressureservomcter having a housing with a movable wall therein,said housing having a fluidinlet communicating one side of the movablewall to a pressure source and spring means bearing at one end on thehousing and at the other. end on the movable wall such that said springmeans is biased against said pressure source to hold said movable wallimmobile so long as said pressure source is communicated to said'inletof .said housing, said a movable wall being operatively connectedto'said force transmitting rod. by a tubular member affxed to saidmovable wall; and

a latching means arranged to hold said tubular memher, said latchingmeans including a pressure responsive element and means to communicatesame to said power brake control means so that said latching means holdssaid tubular member until said power brake control means is operated bythe vehicle operator.

2. Ina brake system a means to automatically increase fluid displacementas is normally attended with pumping of a brake pedalby a vehicleoperator which means comprises:

a power brake means;

a master cylinder operatively connected to the brake pedal, said mastercylinder having a hydraulic fluid reservoir;

a fluid pressure intensifying means including a housing affixed to saidpower brake means and having a bore therein within which a piston isoperatively arranged to divide said bore into a first variable volumecham- 7 her and a second variable volume-chamber, which. housing isprovided with a discharge port for said first variable volume chamberand a valve port and an inlet port for said second variable volumechamber;

conduit means including a first conduit for connecting said dischargeport to said brake system, a second conduit connecting said mastercylinder to said inlet port, and a third conduit connecting said valveport to said hydraulic fluid reservoir;

a force transmitting rod within said power brake means and projectingtherefrom into said housing to be operatively connected with saidpiston;

a fluid pressure servometer having a housing aiiixed to said power brakemeans andwithin which a movable wall is reciprocably mounted, saidhousing having a fluid inlet communicating one side of the movable wallto a pressure source and spring means hearing at one end on the housingand at the other end on the movable wall such that said spring means isbiased against said pressure source 'to hold' said movable wall immobileso long as said pressure source is communicated to said inlet of saidhousing, said movable Wall beingoperatively connected to said forcetransmitting rod by a tubular member projecting from said housing intosaid power brake means which tubular member is affixed to said movablewall; and

a latching means arranged to hold said tubular member, said latchingmeans including a pressure responsive element which is normally biasedby a spring to engage said tubular member and which is communicated by afourth conduit to said second conduit communicated to said mastercylinder so that upon the operation of said master cylinder hydraulicpressure opposes said spring of said pressure responsive element tounlatch said tubular member.

3. In a brake system a means to automatically increase member andthereafter extend into said recess to hold said tubular member and saidmovable wall. 4. In a brake system a means to automatically increasefluid displacement as is normally attended with pumping 5 of a brakepedal by a vehicle operator, which means comprises atively arranged todivide said bore into a first variable volume chamber and a secondvariable volume chamber, which housing is provided with a fluiddisplacement as is normally attended with pumping of a brake pedal by avehicle operator, which means comprises:

a power brake control means operatively connected to the brake pedal;

discharge port for said first variable volume chamber and a valve portand an inlet for said second variable a hydraulic fluid reservoir incommunication with said v volume chamber;

power brake control means; conduit means including a first conduitconnecting a fluid pressure intensifying means including a housing saiddischarge port to the brake system, a second having a bore thereinwithin which a piston is operconduit connecting the inlet port to saidpower brake atively arranged to divide said bore into a firstvaricontrol means and a third conduit connecting said able volumechamber and a second variable volume valve port to said hydraulic fluidreservoir; chamber, which housing is provided with a discharge a forcetransmitting rod operatively connected to said port for said firstvariable volume chamber and a piston; valve port and an inlet port forsaid second variable a fluid pressure servomotor having a housing with avolume chamber; movable wall therein, said housing having a hydraulicconduit means including a first conduit connecting said fluid inletwhich is communicated by a fourth C(mduit discharge port to the brakesystem, a second conto said means for developing a pressure for saidduit connecting said power brake control means to power brake controlmeans such that said pressure said inlet port, and a third conduitconnecting said p g on said movable Wall 011 0H6 Side thereof, valveport to said hydraulic fluid reservoir; and a spring means bearing atone end on the housa force transmitting rod operatively connected tosaid ing and at the other end on the movable wall OPP piston; site theside thereof on which the hydraulic fluid a fluid pressure servomotorhaving a housing with a pressure is impinging such that said springmeans is movable wall therein, said housing having a fluid biasedagainst said pressure source to hold said movinlet communicating oneside of the movable wall able wall immobile so long as said pressuresource to a pressure source and spring means bearing at is communicatedto said inlet of said housing as one end on the housing and at the otherend on th scheduled by said power brake control means, said movable wallsuch that said spring means is biased movable wall being operativelyconnected to said against said pressure source to hold said movableforce transmitting rod by a tubular member affixed wall immobile so longas said pressure source is to said movable wall which tubular member hasa communicated to said inlet of said housing, said rearward projectionformed adjacent the end spaced movable wall being operatively connectedto said from the movable wall with a recess; and force transmitting rodby a tubular member aflixed a latching means operatively connecting saidprojection to said movable wall, said tubular member having of thetubular member to said servomotor housing, a recessed portion and arearwardly facing inclined Said latching means including a Pressureresponsive ramp; element and means to communicate same to said a pawlmechanism including a spring biased piston power brake control means sothat said latching urging a pin having the end opposite the piston meansholds said tubular member until said power beveled forwardly to asimilar angle as said ramp brake control means is operated by thevehicle operinto said recess; and ator. a chamber for said pawlmechanism having an inlet port entering said chamber on a side of saidpiston References Cited by the Examiner opposite that upon which inletport is communicated UN STATES PATENTS to said second conduit so thatwhen a pressurized fluid from said power brake control means enters E-545 X said port of a greater magnitude than the force of 60 nge 9144 Xsaid spring said pin will be removed from said recess 2305302 12/42Mazur 6054'6 X 2,787,122 4/57 Price et a1 60-54.5

to free said movable wall and upon the curtailment of said pressurizedfluid entering said inlet port the spring will once again project saidpawl mechanism to engage said ramp upon the return of said tubularJULIUS E. WEST, Primary Examiner. ROBERT R. BUNEVICH, Examiner,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,195,309 July 20, 1965 Maxwell L. Cripe It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 4, lines 21 and 65, for "servometer", each occurrence, readservomotor line 31, for "affxed" read affixed Signed and sealed this 8thday of March 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. IN A BRAKE SYSTEM A MEANS TO AUTOMATICALLY INCREASE FLUIDDISPLACEMENT AS IS NORMALLY ATTENDED WITH PUMPING OF A BRAKE PEDAL BY AVEHICLE OPERATOR, WHICH MEANS COMPRISES: A POWER BRAKE CONTROL MEANSOPERATIVELY CONNECTED TO THE BRAKE PEDAL; A HYDRAULIC FLUID RESERVOIR INCOMMUNICATION WITH SAID POWER BRAKE CONTROL MEANS; A FLUID PRESSUREINTENSIFYING MEANS INCLUDING A HOUSING HAVING A BORE THEREIN WITHINWHICH A PISTON IS OPERATIVELY ARRANGED TO DIVIDE SAID BORE INTO A FIRSTVARIABLE VOLUME CHAMBER AND A SECOND VARIABLE VOLUME CHAMBER, WHICHHOUSING IS PROVIDED WITH A DISCHARGE PORT FOR SAID FIRST VARIABLE VOLUMECHAMBER AND A VALVE PORT AND AN INLET PORT FOR SAID SECOND VARIABLEVOLUME CHAMBER; CONDUIT MEANS CONNECTING SAID DISCHARGE PORT TO SAIDBRAKE SYSTEM, SAID VALVE PORT TO SAID HYDRAULIC FLUID RESERVOIR AND SAIDINLET PORT TO SAID POWER BRAKE CONTROL MEANS; A FORCE TRANSMITTING RODOPERATIVELY CONNECTED TO SAID PISTON; A FLUID PRESSURE SERVOMETER HAVINGA HOUSING WITH A MOVABLE WALL THEREIN, SAID HOUSING HAVING A FLUID INLETCOMMUNICATING ONE SIDE OF THE MOVBLE WALL TO A PRESSURE SOURCE ANDSPRING MEANS BEARING AT ONE END ON THE HOUSING AND AT THE OTHER END ONTHE MOVABLE WALL SUCH THAT SAID SPRING MEANS IS BIASED AGAINST SAIDPRESSURE SOURCE TO HOLD SAID MOVABLE WALL IMMOBILE SO LONG AS SAIDPRESSURE SOURCE IS COMMUNICATED TO SAID INLET OF SAID HOUSING, SAIDMOVABLE WALL BEING OPERATIVELY CONNECTED TO SAID FORCE TRANSMITTING RODBY A TUBULAR MEMBER AFFXED TO SAID MOVABLE WALL; AND A LATCHING MEANSARRANGED TO HOLD SAID TUBULAR MEMBER, SAID LATCHING MEANS INCLUDING APRESSURE RESPONSIVE ELEMENT AND MEANS TO COMMUNICATE SAME TO SAID POWERBRAKE CONTROL MEANS SO THAT SAID LATCHING MEANS HOLDS SAID TUBULARMEMBER UNTIL SAID POWER BRAKE CONTROL MEANS IS OPERATED BY THE VEHICLEOPERATOR.